1. Field of the Invention
The present invention relates to a method for determining specifications of a fuel cell power generation system constructed of a fuel cell and a capacitor, which are connected in parallel, according to an operational mode of an electric load connected to the fuel cell power generation system, and a fuel cell power generation system with its specifications set using the method.
2. Description of the Related Art
Hitherto, there has been known a hybrid fuel cell power generation system constructed of a fuel cell and a capacitor connected in parallel (refer to, for example, Japanese Unexamined Patent Application Publication No. 2002-305011). Such a fuel cell power generation system is adapted to control the amount of a reactive gas (a reducing gas, such as hydrogen, providing a fuel and/or an oxidizing gas, such as air, which is reacted with the reducing gas to take out electrons) supplied to the fuel cell on the basis of the power required by an electric load connected to the fuel cell and the capacitor.
If the power required by the electric load suddenly increases, and the fuel cell fails to generate sufficient amount of power quickly enough to catch up with the increase in the supply amount of a reactive gas, causing insufficient power supplied from the fuel cell in response to the request for the power, then the capacitor discharges current to make up for the insufficient power supply.
It is required to determine specifications of a fuel cell and a capacitor constituting a fuel cell power generation system so that they match an operational mode of an electric load connected to the fuel cell power generation system. For instance, if the fuel cell power generation system is used as a power source of an electric automobile, then it is necessary to determine the specifications of the fuel cell and the capacitor to provide driving performance, fuel economy, durability, etc. required of the electric automobile according to operational modes of electric auxiliary equipment, including an electric motor for actuating driving wheels and an air conditioner, of the electric automobile.
However, the fuel cell and the capacitor cooperatively supply power to an electric load, making it difficult to determine the specifications of the fuel cell and the capacitor in good balance to meet various requirements according to the operational modes of electric loads.